title: Superparamagnetic iron oxide nanoparticle-labeled cells as an effective vehicle for tracking the GFP gene marker using magnetic resonance imaging.
abstract: BACKGROUND
  Detection of a gene using magnetic resonance imaging (MRI) is hindered by the magnetic resonance (MR) targeting gene technique. Therefore it may be advantageous to image gene-expressing cells labeled with superparamagnetic iron oxide (SPIO) nanoparticles by MRI.
  
  
  METHODS
  The GFP-R3230Ac (GFP) cell line was incubated for 24 h using SPIO nanoparticles at a concentration of 20 microg Fe/mL. Cell samples were prepared for iron content analysis and cell function evaluation. The labeled cells were imaged using fluorescent microscopy and MRI.
  
  
  RESULTS
  SPIO was used to label GFP cells effectively, with no effects on cell function and GFP expression. Iron-loaded GFP cells were successfully imaged with both fluorescent microscopy and T2*-weighted MRI. Prussian blue staining showed intracellular iron accumulation in the cells. All cells were labeled (100% labeling efficiency). The average iron content per cell was 4.75+/-0.11 pg Fe/cell (P<0.05 versus control).
  
  
  CONCLUSIONS
  This study demonstrates that the GFP expression of cells is not altered by the SPIO labeling process. SPIO-labeled GFP cells can be visualized by MRI; therefore, GFP, a gene marker, was tracked indirectly with the SPIO-loaded cells using MRI. The technique holds promise for monitoring the temporal and spatial migration of cells with a gene marker and enhancing the understanding of cell- and gene-based therapeutic strategies.
authors.affiliation: Department of Radiology, Northwestern University, Chicago, Illinois 60611, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Zhang
authors.forename: N
authors.initials: N
authors.lastname: Mascheri
authors.forename: R
authors.initials: R
authors.lastname: Dharmakumar
authors.forename: Z
authors.initials: Z
authors.lastname: Fan
authors.forename: T
authors.initials: T
authors.lastname: Paunesku
authors.forename: G
authors.initials: G
authors.lastname: Woloschak
authors.forename: D
authors.initials: D
authors.lastname: Li
mesh_terms: D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival; D003287:Contrast Media; D003911:Dextrans; D052203:Ferrosoferric Oxide; D015870:Gene Expression; D005819:Genetic Markers; D049452:Green Fluorescent Proteins / Q000032:analysis* / Q000235:genetics; D007501:Iron; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D053768:Metal Nanoparticles; D051379:Mice; D008856:Microscopy, Fluorescence; D010087:Oxides; D013054:Spectrophotometry, Atomic; D013194:Staining and Labeling
chemical_list: D003287:Contrast Media; D003911:Dextrans; D005819:Genetic Markers; D058185:Magnetite Nanoparticles; D010087:Oxides; D049452:Green Fluorescent Proteins; D007501:Iron; C065507:ferumoxides; D052203:Ferrosoferric Oxide